This invention relates to a system for blending (mixing) textile fibers wherein a plurality of serially arranged hoppers, such as feed chutes, feed chambers or the like are charged with fibers in sequence by means of a common pneumatic conveying apparatus arranged overhead. The fibers are removed from the hoppers through the bottom end thereof and are introduced into a common conveying apparatus.
From a given fiber bale lot in a rational manner a fiber blend should be formed to continuously ensure an optimal distribution of the fiber material as regards staple length, fineness, degree of maturity, color, etc. A proper blend is not only fundamental for the manufacture of yarns of unchanging high quality as regards their uniformity, breaking strength and coloring but also improves the running properties of the material during the successive processing. A known apparatus for making such a homogeneous blend is, for example, the Multi-Mixer MPM model manufactured by Trutzschler GmbH & Co. KG, Monchengladbach, Federal Republic of Germany. This known apparatus may have six, eight, ten or twelve hoppers. The multiplier number (tuft blend multiplication or doubling) corresponds to the number of hoppers. By means of the blend doubling there is obtained a particular homogenization of the fiber tufts, that is, the blend doubling has the purpose of compensating for fluctuations in the fiber material.
The essential characteristics of blender efficiency are the hourly output quantities and the quality of blend. According to the blending process performed by the Multi-Mixer MPM, in case of six hoppers a production rate of 600 kg/hour and in case of twelve hoppers a production rate of 1200 kg/hour is achieved. The quality of the blend is decisively determined by how uniformly the defects in the introduced material are distributed in the fiber material mass. It is decisive of the quality of the blend and it is therefore the principal purpose of the blender to evenly distribute the defects in a large fiber quantity, that is, to achieve an equalization of medium and long wave defects in the composition of the introduced fiber material. The greater the fiber material mass in which the fiber defects are to be uniformly distributed the more successful an equalization and thus the better the quality of the blend. Short-wave defects, that is, defects related to small fiber material quantities are in part compensated for during the opening of the bales. Up-to-date bale openers such as the Blendomat BDT model manufactured by Trutzschler GmbH & Co. KG, Monchengladbach, Federal Republic of Germany, limit the error from the start by removing the smallest possible quantities in series from a plurality of bales forming a bale lot.